This invention relates generally to power management for computer systems, and specifically to a system for controlling the power to a video monitor using signals generated by the keyboard controller of the computer.
A wide range of technology has been developed for power management of portable, battery-operated computers. The primary goal of such technology is to reduce battery drain to lengthen the period of time the portable computer can be used before the battery requires recharging.
Far less attention has been given to reducing power consumption of desktop computer systems that rely on a.c. power mains rather than batteries for a source of power. While overall system power consumption must remain below the maximum capacity of the computer's power supply circuitry, there has generally not been any other strong incentive to reduce the power consumption of desktop computer systems.
The United States Environmental Protection Agency (EPA) has recently taken note of the huge waste of power that results from desktop computers that are turned on but are not actively in use. For instance, many computer users leave their computer systems turned on at night, on weekends, and during other periods of prolonged inactivity. In response to this situation, EPA introduced the "Energy Star Computers Program" as an incentive for the computer industry to reduce power consumption of personal computers to 30 watts during periods of inactivity.
A great deal of the technology developed for portable computers can be applied to desktop computers as well to achieve this power reduction goal, but three disadvantages typically arise from application of portable computer power reduction technology to desktop computer systems. Typically, such technology is expensive, so reduction in power consumption is achieved only at significant cost increase. Power-reduction often is achieved through extensive use of the microprocessor of the computer, thus taking away processor capacity for other tasks and requiring a power reduction system that is tailored for a particular computer operating system. Perhaps most importantly, use of portable computer technology in new desktop computers does little, if anything, to address power consumption in the millions of existing desktop computers currently in use, as very little of the portable computer power-reduction technology can be retrofitted to existing desktop computers.
Notably absent from the known power-reduction schemes is a system specifically designed for reducing power consumption of desktop computers that is inexpensive, does not significantly tax scarce processing resources, and can be used with both new and existing desktop computers. Unlike the typical environment in which portable computers are used, in the typical desktop computer environment, external ("peripheral") devices such as color video monitors and laser printers consume far more power than the central processing unit. Therefore, it would be desirable for a desktop computer power-reduction system to control power to such peripheral devices.